Variable compression ratio internal combustion engine



Aug. 16, 1966 w. G. LUNDQUIST 3,266,472

VARIABLE COMPRESSION RATIO INTERNAL COMBUSTION ENGINE Filed June 30, 1964 4 Sheets-Sheet 1 1 INVENTOR;

'- I WlmNGZUmDQU/Sf BY Aug. 6, 1966 w. G. LUNDQUIST 3,

VARIABLE COMPRESSION RATIO INTERNAL COMBUSTION ENGINE Filed June 30, 1964 4 Sheets-Sheet 2 INVENTOR 7V7; ra/v Glu/voau/sz' Aug. 16, 1966 w. e. LUNDQUIST 3,255,472

VARIABLE COMPRESSION RATIO INTERNAL COMBUSTION ENGINE Filed June 30, 1964 4 Sheets-Sheet 3 V ,w I I l INVENTOR.

VARIABLE COMPRESSION RATIO INTERNAL COMBUSTION ENGINE Filed June 30, 1964 Aug. 16, 1966 w. G. LUNDQUIST 4 Sheets-Sheet 4 United States Patent 3,266,472 VARIABLE COMPRESSION RATIO INTERNAL COMBUSTION ENGINE Wilton G. Lundquist, 32 Hollis Drive, Hohokus, NJ. Filed June 30, 1964, Ser. No. 379,298 Claims. (Cl. 123-48) This invention relates to variable compression ratio internal combustion engines and is especially useful in compression-ignition engines.

It is a well established fact that compression-ignition engines, such as the diesel, can be operated with much greater efliciency and over a wider range of fuels (e.g. diesel oil, kerosene, gasoline, etc.) if some means for varying the compression ratio is provided. Also, a substantial increase in output can be achieved without a corresponding increase in maximum combustion pressure. For example, providing a high compression ratio improves cold starting and light load conditions, while for other conditions a lower compression ratio is desirable.

In general, the invention contemplates the use, in conjunction with a U-type cylinder provided with a pair of cylinder bores having a common combustion chamber including a cross-over passage interconnecting the pair of cylinder bores; of a plunger slidably mounted for movement into said cross-over passage for varying the effective volume of the common combustion chamber, fluid pressure means for moving said plunger into said cross-over passage and means for controlling the retractile movement of said plunger at a predetermined cylinder combustion pressure and/or compression pres sure imposed on the forward end of said plunger. More specifically, means are provided, for suitable adjustments of the fluid pressure system, to automatically control a predetermined cycle of variation of the compression ratios, while at the same time providing manual control means by which the operator may effect a change in the compression ratio during operation of the engine.

Objects of the invention include: Improved means for varying the compression ratio of internal combustion engines; means for automatically effecting said variations; and means for controlling the flow of inlet charges and exhaust gas between a pair of U-type cylinder bores to vary the percentage of fresh air which can be trapped during each cycle.

FIG. 1 is a front elevational end view of an engine embodying the invention;

FIG. 2 is a top plan view of one of the cylinder blocks of the engine of FIG. 1, with parts broken away to show some of the internal parts and also showing in somewhat schematic form an important feature of the invention;

FIG. 3 is a side elevational view of the upper part of the cylinder block shown in FIG. 2;

FIG. 4 is a sectional view taken along the sectional line 44 of FIG. 3;

FIG. 5 is a sectional view taken along the sectional line 5-5 of FIG. 4, as Well as along the sectional line 55 of FIG. 2; and

FIG. 6 is a sectional view taken along the sectional line 6-6 of FIG. 4.

Referring to FIG. 1, the engine is generally designated as 10 and comprises a plurality of cylinder blocks designated in general as A, B, C and D. In the present embodiment, the cylinder blocks are symmetrically disposed about an axis of symmetry designated AS. The engine herein disclosed by way of example is of the type more fully described in my Patent No. 2,989,022 and only such features as are germain to the present invention will be described in detail.

In the embodiment of the invention shown herein the engine is a two-cycle engine of the compression-ignition or diesel type, however, it is contemplated that certain aspects of the invention may be usefully employed in four-cycle engines, as well as in spark ignition engines.

Each of the cylinder blocks is U-type (FIG. 5) having a pair of cylinder bores 11 and 12 and a common combustion chamber 13 including a cross-over passage 14 interconnecting the cylinder bores 11 and 12. The cylinder bore 11 is provided with an exhaust port 15 and the cylinder bore 12 is provided with an intake port 16. A piston 17 is disposed in the cylinder bore 12 and controls the intake port 16 and a piston 18 is disposed in the cylinder bore 11 and controls the exhaust port 15. The U-type cylinder block comprises a main body portion 19 and a Water jacket 20 providing a water jacket space 21 therebetween for the purpose of cooling the cylinder head by water or other suitable cooling fluid.

Each of the cylinder blocks A, B, C and D (FIG. 1) comprises the same arrangement as above described with reference to cylinder block A. Operating fuel is supplied by means of fuel pipes such as 22 from which the fuel is introduced directly into the common combustion chamber by a fuel injection assembly such as 23.

Means for varying the effective volume of the combustion chamber to thereby vary the compression ratio of the engine will now be described. It being noted that the features hereinafter described with reference to cylinder block A are also provided with respect to the other cylinder blocks B, C and D and are preferably actuated simultaneously.

Referring more particularly to FIGS. 4 and 5: The cylinder body 19 is provided with a threaded bore 25 extending in an axial direction transverse the cross-over passage 14 and into this threaded bore there is disposed a plunger housing 26 provided with cooperating screw threads and being suitably sealed to provide a fluid-tight connection between said housing and cylinder head. The plunger housing is provided with a smooth bore 27 extending from its inner end outwardly for receiving a plunger 28 and suitable ring seals are provided between the housing bore 27 and plunger 28 to effect a fluid-tight seal therebetween during reciprocation of said plunger.

The outer end of the housing 26 is provided with a counterbore 29 which terminates inwardly in a shoulder 30. The outer end of the housing 26 is closed by means of a housing head 31 which serves to form a closed fluid pressure chamber within the housing 26. The head 31 comprises an annular sleeve 32 in threaded engagement with the outer end of the housing 26. A conduit member 33 (see also FIG. 6) at its lower end is provided with a portion encircling the housing 26 and is tightly clamped in position between the inner face of the sleeve 32 and a housing shoulder 34 with copper gaskets such as 35 interposed adjacent opposite faces of the member 33 and which serve the joint purpose of providing a fluid seal between the housing 26 and its head 31 and also a fluidtight seal between the housing 26 and the encircling member 33, for purposes to be hereinafter described. The head 31 is also provided with an axially disposed hollow stem 36 which extends inwardly within an axial bore 37 provided in the plunger 28. The inner end of the stem 36 is provided With a head portion which is in fluid-tight sealing engagement with the bore 37 of the plunger 28 by means of sealing rings such as 38. The outer end of the stem 36 is reduced in diameter to provide an annular space 39 which forms a part of the closed fluid pressure chamber within which the plunger 28 is operatively disposed. A tube 40 is rigidly mounted at its outer end on a plate 41 and is adapted to be connected to a source of cooling fluid such as water. The tube extends axially inwardly within the bore 37 of the plunger 23 in spaced relation to the hollow bore in the stem 36 to provide for the flow of cooling fluid into the plunger 28 and thence outwardly to return to the water cooling chamber 21, as indicated by the arrows. The body 26 is provided with cooling fins 42. The outer end of the plunger 28 is provided with a flange 28' adapted to engage the housing shoulder 30 to limit the inward stroke of the piston so that its inner end moves only to a predetermined position indicated by the heavy broken line L, to assure that the cross-over passage 14 will not be completely closed at any time.

Means for operating the plunger 28 will now be described. In the present embodiment, hydraulic pressure fluid is used since under normal conditions this is the preferred pressure fluid. However, it is contemplated that pneumatic pressure fluid may be employed if the same is under a suitably high pressure to overcome the desired maximum cylinder pressure.

The conduit member 33 (FIGS. 4 and 6) is provided with an upwardly extending stem 50 passing through a packing gland 51 providing a seal. The upper end of neck 50 forms part of a control valve assembly designated in general as 52. The stem 50 has a passage 53 in communication with an inlet passage 54 for receiving pressure fluid passing through a check valve 55 (FIG. 2). The passage 53 extends above the inlet passage 54 where it is enlarged to form a chamber 56 from which radial ports 57 communicate with an outlet passage 53. A needle valve 59 is adjustable by an arm 60 from closed position to the desired degree of open position so as to control the passage of pressure fluid through the outlet port 58. The outlet port 58 is connected by means of a pipe 61 (FIG. 2) to a suitable pressure fluid system now to be described with reference to the schematic illustration. Pressure fluid is supplied from a pressure pump 62 and/or a pressurized fluid supply tank 63. Pressure regulating valves 64 and 65 are provided for controlling the system in the manner described below.

Before starting the engine, fluid under suflicient pressure is introduced through check valve 55 and inlet passage 54 into the passage 53 from which it passes through a registering port 43 into the closed fluid chamber 29 forcing the plunger 28 to move inwardly across the crossover passage 14 up to the line L (FIG. 4). When the engine starts to operate, cylinder combustion pressures and/or compression pressures act to force the plunger back into the housing against the pressure of the actuating fluid. The rate of plunger 28 retraction or the position of the plunger, if it is desired to be stopped at partial retraction, may be controlled by adjusting the needle valve 59 to permit controlled leakage out through pipe 61, or to shut off leakage entirely, to thereby stop the plunger at a partially retracted position. Thus the engine can be started with a high compression ratio, which automatically changes to a predetermined lower ratio after the engine is started.

The invention may also be used to limit maximum cylinder pressure during engine operation under high power conditions. To accomplish this, a suitable high pressure (empirically related to the desired maximum cylinder pressure) is applied via check valve 55 and by suitable adjustment of the control valves 64 and 65 and the needle valve 59, the actuation of the plunger 28 will automatically control the maximum cylinder pressures to a pre-selected value.

In addition to the variation of the volume of the combustion chamber by movement of the plunger 28, the movement of the plunger in the cross-over passage 14 controls the flow of inlet charge and exhaust gas between the U-type cylinder bores such as 11 and 12 to thereby vary the percentage of fresh air which can be trapped during each cycle.

What I claim is:

1. In an engine the combination of a U-type cylinder block having a pair of cylinder bores and a common combustion chamber including a cross-over passage interconnecting the pair of cylinder bores, one of said cylinder bores in said U-type cylinder being provided with an inlet port and the other of said cylinder bores with an exhaust port, and means for controlling said ports; means for varying the eifective volume of the common combustion chamber comprising a plunger slidably mounted in said cylinder block for movement into said cross-over passage, stop means limiting the maximum movement of said plunger into said cross-over passage so that said passage is never closed, and fluid pressure means for moving said plunger into said cross-over passage.

2. An engine comprising a U-type cylinder block having a pair of cylinder bores and a common combustion chamber including a cross-over passage interconnecting the pair of cylinder bores, one of said cylinder bores in said U-type cylinder being provided with an inlet port and the other of said cylinder bores with an exhaust port, and pistons disposed in said cylinder bores and controlling said ports; characterized in that said cylinder block has a plunger slidably mounted therein for movement into said cross-over passage to thereby vary the effective volume of the common combustion chamber, stop means limiting the maximum movement of said plunger into said crossover passage, fluid pressure means for moving said plunger into said cross-over passage so that said passage is never closed, and means for automatically controlling the inward and outward movement of said plunger to predetermine the compression ratio variation.

3. A two-cycle compression-ignition engine comprising a plurality of U-type cylinder blocks symmetrically disposed about a common axis and each having a pair of cylinder bores and a common combustion chamber including a cross-over passage interconnecting the pair of cylinder bores, one of said cylinder bores in each said U-type cylinder being provided with an inlet port and the other of said cylinder bores with an exhaust port, said pistons disposed in said cylinder bores and controlling said ports; characterized in that each aid cylinder block has a plunger slidably mounted therein for movement into said cross-over passage to thereby vary the eflective volume of the common combustion chamber, stop means in each cylinder block limiting the maximum movement of said plungers into said cross-over passages so that said passages are never closed, fluid pressure means for moving said plungers into said cross-over passages, and means for automatically controlling the inward and outward movement of said plungers to predetermine the compression ratio variation.

4. An engine as set forth in claim 3 in which each said plunger is slidably disposed in a bore provided in a housing which has an inner end in sealed engagement with a corresponding cylinder block, said housing having an outer closed end providing a pressure fluid chamber receiving the outer end of said plunger and the inner end of said housing bore being in communication with said common combustion chamber and in register with said cross-over passage, a conduit providing a pressure fluid passage in communication with said pressure fluid chamber and valve means in communication with said pressure fluid passage, said valve means providing one way flow of pressure fluid into said plunger chamber and having adjustable means for controlling the reverse flow of said pressure fluid to thereby determine the retractile movement of said plunger.

References Cited by the Examiner UNITED STATES PATENTS 2/1949 Gehrandt 123-48 8/1956 Humphreys "123-48 6 FOREIGN PATENTS 5/ 1936 France. 9/ 1920 Germany. 3/ 1932 Germany. 4/ 1959 Italy.

MARK NEWMAN, Primary Examiner.

W. E. BURNS, Assistant Examiner. 

1. IN AN ENGINE THE COMBINATION OF A U-TYPE CYLINDER BLOCK HAVING A PAIR OF CYLINDER BORES AND A COMMON COMBUSTION CHAMBER INCLUDING A CROSS-OVER PASSAGE INTERCONNECTING THE PAIR OF CYLINDER BORES, ONE OF SAID CYLINDER BORES IN SAID U-TYPE CYLINDER BEING PROVIDED WITH AN INLET PORT AND THE OTHER OF SAID CYLINDER BORES WITH AN EXHAUST PORT, AND MEANS FOR CONTROLLING SAID PORTS; MEANS FOR VARYING THE EFFECTIVE VOLUME OF THE COMMON COMBUSTION CHAMBER COMPRISING A PLUNGER SLIDABLY MOUNTED IN SAID CYLINDER BLOCK TO MOVEMENT INTO SAID CROSS-OVER PASSAGE, STOP MEANS LIMITING THE MAXIMUM MOVEMENT OF SAID PLUNGER INTO SAID CROSS-OVER PASSAGE SO THAT SAID PASSAGE IS NEVER CLOSED, AND FLUID PRESSURE MEANS FOR MOVING SAID PLUNGER INTO SAID CROSS-OVER PASSAGE. 